Prominent New Jersey governor Chris Christie is widely tipped as a leading contender for the Republican presidential nomination in 2016.EPA/David Gard

The 2016 presidential race has already begun, as evidenced by politicians such as the mayor of Los Angeles dropping by to visit the luncheon of the Iowa contingent at the Democratic National Convention. (Iowa is the state with the first votes for president in the primary calendar.)

Anyone seriously interested in running four years from now is already considering how to build the organization and fortune necessary to do so. Remember, each side spent $1 billion trying to win this year.

We don’t know what will happen in the US or internationally over the next four years, and another economic or military crisis could reshape the race. History and suggests that Republicans will have another good year in the congressional and gubernatorial elections of 2014, diminishing the pool of possible big name Democratic entrants. But the US economy should also be stronger and popular provisions of the new health care law also go into effect in 2014, perhaps leading to more public support for Obama and Democrats. Who knows?

But as of Election Day 2012, here are the Sweet 16 looking to 2016:

The Democrats

Joe Biden: The VP made what was treated by reporters as a joke the other day when he told a skeptical voter that, after the new health insurance regulations come into effect, “you’ll be voting for me in four years”. The assumption has been that Biden would be like Dick Cheney and not seek the White House for himself. But who could stop him from going for it if he really wanted to, particularly after he is credited by Democrats as having stopped the bleeding after the disastrous first presidential debate?

Hillary Clinton: The Clintons are no longer flatly denying that she will run. You know what that means. With the right mix of independence from the Obama team and support from it, and without the Iraq War albatross that sunk her in 2008, what could stop the person who is currently the most popular public official in America? (Of course, I thought back in 2001 that no one could stop her in 2008). Her replacement as the junior senator from New York, Kristen Gillibrand, has announced that she hopes to be the chair of the Hillary 2016 campaign (but is being mentioned as a possible candidate herself if Clinton demurs).

Mark Warner: Back in 2006, the extremely popular and wealthy former governor of Virginia was going to be the anti-Hillary, but he passed on the race for family reasons and Obama almost immediately thereafter jumped in. Now a senator, Warner has made it clear that he is not enjoying his new job. This is being interpreted as an interest in returning to the Virginia state house, but then why is he visiting those Iowans? Probably the early Democratic frontrunner if Biden and Clinton both pass on the race.

Brian Schweitzer: The outgoing governor of Montana is innovative: he came up with the much-copied idea of taking busloads of senior citizens up to Canada to buy cheaper prescription drugs during his senate run in 2000; he dresses and talks like a cowboy, including accompaniment by a hunting dog, to maintain support in his frontier state and openly admits that he is doing so; and as a former oil engineer in Saudi Arabia he is an advocate for existing technology to turn domestic coal into gasoline, which could get him general election support in Appalachian states that have been lost to Democrats since Bill Clinton. Obama gave him a featured speech at the 2008 convention and he is known to be looking hard at 2016.

Martin O’Malley: He came out of nowhere to become mayor of Baltimore (benefiting from being the only white candidate in a race in which several African-Americans split the vote) and his success has led to two terms as governor of Maryland. Known to be organizing a bid, he has been giving “centrist” interviews to national media lately that have not played well with online progressive activists.

Amy Klobuchar: She is about to cruise to a second term as senator from Minnesota, having easily dispatched a top Republican congressman the first time. Formerly the county attorney for the region encompassing Minneapolis, Klobuchar is now on the circuit in neighboring Iowa too and would benefit from regional favoritism in its caucus. She might have a star turn as a solid Midwestern candidate or at least put herself in contention for VP.

Antonio Villaraigosa: He has been relatively popular as the mayor of Los Angeles, but mayors don’t get elected president. A recent scandal involving an extramarital affair won’t help either. But he’s making the rounds, possibly to position himself as VP candidate, which would make him the first Hispanic on a national ticket.

Andrew Cuomo: The governor of New York, and the son of another one who could have been the nominee in 1992 but ultimately decided against running. Like O’Malley, Cuomo has irritated the Democratic activist base by capitulating to Republicans in the state assembly on issues such as redistricting, and his star seems to be fading.

Corey Booker: The African-American mayor of Newark is seen as both effective and tough – not long ago he was burned while running into a house that was on fire to save its occupant, and he is currently opening his own home to members of the public left without power or shelter by Hurricane Sandy. While he is publicly looking at 2016, more realistically he might first challenge Republican Chris Christie for the governorship of New Jersey next year, or else run for a senate seat if 90 year old Democrat Frank Lautenberg retires in 2014.

The Republicans

Paul Ryan: Assuming that he isn’t elected VP, Ryan would seem to be the natural GOP leader for 2016, and Republicans nearly always nominate their early frontrunner. He will have the name recognition and strongly appeals to libertarian Tea Party conservatives. His social services cutting budget plan, which has proven to be a liability with the general electorate, would endear him to supply-side tax cutters in the primary. But I would imagine that his candidacy would create a natural opening for a Christian social conservative alternative.

Jeb Bush: More ambitious than his older brother George W., James Earl (“JEB”) Bush likely would have been the one to be president (according to their mother!) if he hadn’t been narrowly defeated for Florida governor by a canny Democrat in 1994 while W. was winning in Texas. Elected to two terms beginning in 1998, and despite the controversy of the 2000 Florida recount, Jeb remains popular in Florida and with national Republicans. He has passed up opportunities to run for Senate and his father recently stated that he is leaning toward a 2016 run. But is America ready to let another Bush – the third in 25 years – into the White House?

Chris Christie: Many Republicans wanted the pugnacious governor of New Jersey to be their nominee this year when they were casting about for someone not named Romney. Romney staffers have recently revealed that Christie was going to be the VP choice until Mitt thought twice, worrying that Christie would be an attention hog on the campaign trail and unreliable in the administration. Apparently he was right: Christie’s speech at the RNC was panned because he barely mentioned Romney, and Christie is taking a lot of conservative flack at the moment for praising President Obama’s response to Hurricane Sandy and therefore “hurting” Romney in the week before the election.

The situation makes me think of former governor Charlie Crist of Florida, who was castigated for embracing Obama after receiving federal hurricane aid, driven out of the party where he had been an aspiring star, and ended up as a speaker at this year’s DNC. Christie may have played well to independents this year, but in so doing it would seem he has sunk himself with the conservative activists who dominate Republican primaries. Six months ago the likeliest 2016 nominee, Christie is probably deeper underwater now than parts of the Jersey Shore.

Rand Paul: His father, Texas congressman Ron Paul who was the Libertarian Party nominee in 1988 and sought the GOP nod in 2008 and 2012, is retiring and taking credit for injecting the libertarian streak into conservatism today that characterizes the Tea Party. His son, named for objectivist philosopher/novelist Ayn Rand, whom Paul Ryan credits as inspiring his political career, was elected as senator from Kentucky in 2010 as a political novice, crushing two high profile elected state officials in both the primary and general elections and being the first major Republican in 2010 to declare himself of the Tea Party.

Some speculate that Ron Paul’s decision to go quietly into the night and convince his fanatical supporters not to disrupt the national convention with platform demands was intended to buy favor for Rand to seek national office in 2016 or 2020. He would start with a small but rabid core of support. A possible alternative for hardcore conservative activists might be a controversial Tea Partier, African-American freshman Representative Allen West of Florida, who would be farther to the right than even the 2012 crop of Republican primary candidates, and whose anti-Muslim tirades could make him the de facto evangelical Christian candidate.

Marco Rubio: The Florida senator and former state house speaker for whom Sunshine State conservatives abandoned Charlie Crist has been mentioned as potential national star for years. He ruled out running for VP in 2012, but is considered vital to the future of a Republican Party that desperately needs to make up ground among the burgeoning Hispanic electorate.

However, the Cuban-American lawmaker made some missteps this year in statements about when his family came to America and is actually facing a clique of conservative birthers arguing that he is not constitutionally eligible for the presidency. If he runs, he will face that antipathy on the far right and might be squeezed out as Tea Party favorite by Ryan or Paul. If the GOP really wants a Hispanic on the ticket and Rubio demurs again, look for attention to be paid to New Mexico’s Governor Susana Martinez or soon-to-be Texas senator Ted Cruz.

Scott Walker: The Wisconsin governor survived a tough recall election triggered by his efforts to strip unions in the Badger State of collective bargaining ability. In the process he became a hero to conservatives nationwide and is making the rounds in neighboring Iowa. If Walker passes, it could leave an opening for Virginia’s Bob McDonnell as a conservative governor.

Rob Portman: George W. Bush’s Director of the Office of Management and Budget won a senate seat in Ohio in 2010, where he had previously served as a congressman. Pundits called Portman the likeliest and most solid possibility for the VP spot in 2012, but Romney felt that he needed a bold choice and one that would energize conservatives. With Portman leading the ticket, the GOP would begin the general election favored to carry crucial Ohio.

Nikki Haley: The 40 year old governor of South Carolina (the most vital early state in the Republican primary calendar and one she would presumably win) has had spectacular success as an Indian-American woman in one of the most deeply conservative and racially charged states in the nation. She is mentioned as a potential national star, but she still faces questions about her commitment to Christianity given that she is a convert and still occasionally attends Sikh worship services. I would have given her spot to Bobby Jindal, the first Indian-American governor (of another Deep South state, Louisiana) who wears his adopted Christianity on his sleeve and would have filled a niche for evangelical primary voters. But his luster has faded since a weak nationally televised address responding to Obama’s first State of the Union speech.

This roster has surprised me in that there are fewer major Democrats and more Republicans than I had thought, and that none of the prominent Republicans fits the major religious social conservative niche in the Republican primary electorate. And the potential for Clinton-Biden and Ryan-Bush battles would be exciting to any political junkie.

Still this is only the list as of the first Tuesday after the first Monday in November (Election Day) 2012. I hope to revisit it four years from now to see how these 16 did or if any later entrants surprised. Not all of them will run in 2016, but you can bet that by the end of this week they will already be part of the Conversation about the next turn in American politics.